Mechanical stoker.



A. B. HOFMANN.

MECHANICAL STOKBR.

A P.PLIOATION FILED MAY 8, 1011.

. Patented Mar. 5, 1912.

2 SHEETS-SHEET 1.

j/ZTr-ny.

COLUMBIA PLANOORAI'" C0" WASIIINUTON. D- C A. B. HOFMANN.

MECHANICAL STOKER.

APPLICATION FILED MAY 8, 1911.

2 SHEETS-SHEET 2.

Patented Mar. 5, 1912.

UNITED STATES PATENT OFFICE.

ALFRED EDWARD HOFMANN, OF LUCERNE, SWITZERLAND.

MECHANICAL STOKER.

To all whom it may concern:

Be it known that I, ALFRED EDWARD Hor- MANN, a citizen of the Republic of Switzerland, and residing at Muhlemattsti 1, Lucerne, Switzerland, have invented new and useful Improvements in Mechanical Stoker's, of which the following is a specification.

My present invention relates to mechanical stokers in which the fuel is fed from a suitable hopper to an inclined grate, the fuel being admissible thereto proportionate to consumption.

That the consumption of fuel may be such as to obtain a substantially uniform boiler pressure, an object of my invention is to provide means, responsive to the rise or fall of boiler pressure, to regulate the air admissible through the grate.

Further objects of my invention are to regulate the amount of fuel admissible to the grate which coacts with the draft regulating means to provide for economical combustion of fuel.

A further object of my invention is to periodically so incline the grate plates that slag or the like is quickly removed there from and restore the same to their normal position.

I attain these objects by the construction and arrangement of parts shown in the accompanying drawings, in which Figure 1 is a longitudinal section through a portion of a boiler and the stoker, embodying my invention, in connection therewith. Fig. 2 is an elevation looking in the direction of the grate plates. Fig. 3 is an enlarged detail of part of the mechanism used in actuating the grate plates for removal of slag. Fig. 1 is a fragmentary view of a portion of the stoker, parts being shown in section to bring out details of construction. Fig. 5 is an enlarged detail of the same. Fig. 6 is a side elevation of the fuel hopper control means. Fig. 7 is a detail View of the same, parts being shown in section to bring out details of construction.

Similar characters refer to similar parts throughout the several views.

In the drawings, A designates a boiler which is provided with a fire box B. ithin the fire box, a plurality of hollow grate plates 1 are pivotally connected through the arms 2, to an inclined supporting member 4. The pivot point of the grate plates is indicated at 3 and radially to which extend Specification of Letters Patent.

Application filed May 8, 1911.

Patented Mar. 5, 1912.

Serial No. 625,930.

arms 12 pivoted to a movable bar 13. The supports 2 are hollow and are open to the hollow grate plates as indicated at 2 in Fig. 1. A suitable conduit 5 forms a communication through the several hollow supports which allow a current of water to flow from plate to plate. The inlet to the plates is shown at 6 and the current follows the course indicated by arrows in Fig. 2. From the uppermost grate plate the current is conducted through a tubular member 7 to a hollow plate 8, from which it is conducted to fore-boiler 10. The fore-boiler surrounds the fire box, and a communication 11 is interposed between the fore-boiler and the main boiler A.

As means for adjusting the position of the grate plates for varying the quantity of air admissible therethrough to obtain a substantially uniform boiler pressure, by regulating the draft, the following mechanism is provided: A cylinder 17, provided with a piston 16, has a pipe connection 18 with the main boiler A through which the rise and fall of pressure therein affects the cylinder accordingly. The piston 16 is connected to the grate structure for regulating the position of the grate plates through links 1 1 and 15, the former of which is rigidly secured to one of the arms 12. Inasmuch as all of the arms 12 are pivotally connected to the movable bar 13 simultaneous movement of all of the grate plates results upon movement of the piston 16.

In order to adapt the cylinder to produce movement of the piston 16 for obtaining a substantially uniform boiler pressure, the piston 16 is provided with tension springs 20 having bolts 20 which pass through a plate 1%) and are held in an adjusted position by nuts 20. From the foregoing description it will be seen that when the boiler pressure rises, a proportionate rise of the piston 16 is produced, which through the links 141. and 15 causes the grate plates to swing upon their pivots 3, thus reducing the space between the plates limiting the quantity of air therebetween.

Coacting with the means for regulating the draft, mechanism is provided for regulating the amount of fuel admissible to the grate structure according to consumption. This mechanism includes a fuel hopper 22 provided with an opening 21, arranged to deliver to an accumulating chamber C disposed above the grate structure. The opening 21 of the fuel hopper is controlled by an oscillatable shutter 23 which may be oscillated through the following described mechanism. A bell crank lever is pivoted at 26, the arm 25 of which is connected to the shutter through the link 24, the arm 27 is provided with a pin 32. A vertical reciprocating and oscillatable arm 29 receives movement through a disk 42 carried by the shaft 43; The oscillation of the arm 29 is limited with respect to the shaft 26 by means of the links 28, which are free to move about the shaft 26 and pivoted to the arm 29. The arm 29 carries a pivotally mounted catch member 30, a slot 31 of which is positioned to receive the bolt 32' and through which movement of the arm 29 may be transmitted to the arm 27 of the bell-crank lever. The outlet of the accumulating chamber C is controlled by a plate 40 secured to the shaft 39. This plate is normally held in contact with the hollow plate 8, which forms one of the walls of the accumulating chamber, by an arm 37 rigidly secured to the shaft 39 and provided with a tension spring This spring normally positions the plate 40 in contact with the hollow plate 8. When the accumulated load of fuel upon the plate 40 overcomes the resistance of the spring 38, the plate 40 assumes a position indicated in dotted lines of Fig. 6, and actuates a bell-crank lever pivoted at 34, the arm of which is connected by a link 36 to the arm 37. The arm 33 of the bell crank lever engages an extension of the member 30 and forces thesame out of engagement with the bolt 32. Such action renders the arm 29 inactive for oscillating the shutter 23 until the plate has again assumed a position closing the opening of the accumulating chamber.

The fuel leaving the accumulating chamber is conducted to the grate plates through inclined plate 41, and as the fuel is consumed the plate 40 is permitted to allow delivery of fuel from the accumulating chamber as soon as a predetermined load of fuel is contained therein.

The hollow plate 8 is provided with a handle 8 as shown in Fig. 6, which allows the plate to be swung for admission of wood orthe like for starting a fire. Means for periodically oscillating the grate plates for the removal of slag or the like may be provided, the grate plates being restored to their normal position controlled by the boiler pressure after actuation of said means. Such means includes a wheel 45, secured to the shaft 43 which is driven by means of pulleys 46 and provided with a facial lug 44. The lug is adapted to engage the hooked end of a member 47 pivoted to the movable bar 13 and carry the same with it through a partial revolution of the wheel 45. Through movement of the member 47 the grate plates are drawn to form a substantially uniform inclined surface as indicated in Fig. 4, the member 47 being released from the lug 44 by a projection 48, carried by the boiler structure. Upon being released the member 47 allows the grate plates to quickly assume a normal position dependent upon the boiler pressure.

It is not desirable that the grate plates should be actuated upon each revolution of the wheel 45, therefore, the member 47 is held out of the path of the lug 44 by the following construction and arrangement of parts for a predetermined period.

The member 47 is provided with a plurality of projections 63, the uppermost projection engaging a frame structure 60, and carrying the same with it upon movement of the member 47. The frame 60 is mounted on a plunger 51 operating within a cylinder 49. The cylinder 49 is adapted to accommodate the plunger 51 through the chamber and a valve 56 in the chamber 55, a communication between the chambers 50 and 55 being formed by the by-passes 52 and 53, the latter of which may be inclosed by a ball member 54. The valve 56 has an inclined surface 55' and is adaptedto be actuated by a bell-crank lever 57, the arm 58 of which is connected with the movable bar 13 through the link 59.

The cylinder 49 is adapted to contain a fluid which may be transferred from the chamber 50 to the chamber 55, the rate of flow being regulated through the valve 56. The extent of opening formed by the inclined surface 55 of this valve is automatically regulated according to the position of the movable bar 13, that is, when the grate plates are engaging each other as indicated in Fig. 4, the fluid has free access to flow within the chamber 55, the communication therebetween being gradually closed as the grate plates assume a position in stepped relation to each other. The frame 60 carries with it a sector 62, pivoted on the shaft 43, through a link 61. This sector engages the projection 63 when the member 47 is disengaged from the lug 44, (see Fig. 3), and forces the same out of the path of the lug 44. Upon upward movement of-the frame 60, the plunger 51 draws the fluid within the chamber 50 and upon downward movement of the plunger the fluid is gradually transmitted to the chamber 55. Until the sector- 62 assumes a position shown in Fig. 4, the. member 47 is held out of the path of the lug 44, thus the wheel 45 is allowed to revolve a number of times before the oscillation of the grate plates is effected for the removal of slag. The plunger 51 returns to its normal position through gravity and may be provided with detachable weights 64, shown in Fig. 5, by which the return of the plunger may be adjusted to actuate the grate;

plates at predetermined periods. The slag is removed from the fire box by means of a roller 66 provided with longitudinally extending bars 67. A plate 72 is pivotally mounted as at 7 3 in close proximity with the roller 66 and is allowed to assume a position, indicated by dotted lines in Fig. 1, to permit the slag to drop below the fire box. The roller 66 is rotated by means of links 7 0 and 71, the former carrylng a pawl 69 engaging a ratchet wheel 68 carried by the roller, and the link 71 being pivoted to the movable bar 13. By this construction, when the bar 13 is actuated, movement thereof is transmitted to the roller 66, which turns upon the shaft 65 through the ratchet and pawl.

Inasmuch as the bars 4 are pivoted with an axis coinciding with that of the roller 66, the whole grate structure may be lowered, as indicated by dotted lines in Fig. 1, to facilitate entrance to the fire box.

From the foregoing description it is made manifest that I provide a mechanical stoker which may automatically regulate the position of the grate plates, for admission of air therebetween, according to the boiler pressure; that the means for actuating the grate plates is adjustable to provide for a substantially uniform boiler pressure when the stoker is active; that the fuel conductible to the fire box isregulated according to consumption thereof, and that slag or other accumulations may be removed from the grate at certain periods, the grate assuming a normal position for regulating the draft according to the boiler pressure after such action has taken place.

I claim:

1. In a mechanical stoker, the combination of a grate structure including a plurality of pivotally mounted plates adapted to coact with each other to form a substantially uniform inclined surface, or to be swung in spaced stepped relation to each other, a rod operatively connected to said plates for actuating the same, a revoluble element provided with a lug, a hooked member carried by said rod and normally out of the path of movement of the said lug of said revoluble element, and means actionable at predetermined periods and independently of said revoluble element, for periodically positioning said hooked member in the path of movement of said lug, whereby said plates are actuated, through the engagement of the hooked member and lug, to remove slag or the like.

2. In a mechanical stoker, the combination with a boiler and furnace therefor, of a grate structure includin a plurality of pivotally mounted plates'a apted to coact with each other to form a substantially uniform inclined surface, or to be swung into spaced apart stepped relation to each other, means for imparting movement to said grate plates, a hooked member carried by said means, mechanism operatively connected to said means for actuation thereof to decrease or increase the space between said plates relative to the rise or fall of boiler pressure, a revoluble element provided with a lug adapted to engage said hooked member, mechanism for positioning said hooked member in the path of said lug whereupon said grate plates are actuated, and means operatively connected to said first mentioned means for regulating said second mentioned mechanism to position said hooked member in the path of said lug after variable periods, the intervals between action decreasing or increasing relative to the rise or fall of boiler pressure.

In testimony whereof I aflix my signature in presence of two witnesses.

ALFRED EDWARD HOFMANN.

"Witnesses:

HEINRICH RINDERKNECHT, AUGUST Knlnoo.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents. Washington, D. G. 

